traction

ben james · Post by **ben james** » Mon Jul 17, 2006 10:50 pm

hope you read this greg watters, i remember you telling me that you factor in about 10% wheelspin into your gearing on your busa. trying to remember what you said as i'm working out some gearing for my kwacka.
regards ben

Greg Watters · Post by **Greg Watters** » Tue Jul 18, 2006 10:05 am

Thats right Ben, depends on conditions of course .
Problem is if you only get 3% then your overgeared for the conditions.
i usually have 2 front and 2 rear sprockets to be able to change ratio's to suit.
On a speedo calibrated and marked for Kims 175 licence run, 166 was run, and Kim thought she was fairly close to the mark.
Track was a bit average by that time . And the speedo had been calibrated with a 100mph run with probably little or no wheelslip.

Stayt`ie · Post by **Stayt`ie** » Tue Jul 18, 2006 8:28 pm

g`day ben, have you had kermit on the dyno :?:

ben james · Post by **ben james** » Tue Jul 18, 2006 10:31 pm

no ron, was planning to. i know i don't have much power out of that motor so i was going to take it easy on the lead weight. about 50kgs behind the swingarm pivot underneath the swingarm, will be 10 kg sheets so i can subtract weight if it's too much. i have a suspicion that the swingarm might be to long and the swingarm pivot is below the rear axle horizontal line. that type of chasis just may not be suitable for salt work. but after seeing john pudney take a stock z1000j motor to 172 mph i still have some hope. was going to start on new motor soon. hey why did you ask ronnie.
ben

gazza414 · Post by **gazza414** » Thu Jul 20, 2006 3:32 pm

On my stock Busa this year I had no wheel spin at all --ran high 190's everytime --no ballast

Last year at 217mph also no ballast on the "other" :roll:

bike

ben james · Post by **ben james** » Thu Jul 20, 2006 8:45 pm

hi gaz, is that a stock length swingarm.
ben

gazza414 · Post by **gazza414** » Fri Jul 21, 2006 10:11 pm

std swingarm Ben and wheelbase

Stayt`ie · Post by **Stayt`ie** » Fri Jul 21, 2006 11:05 pm

ben, i recon a long swingarm (without ballast) dose contribute to wheelslip, for example my zx with standard arm 335lbs at rear wheel, put 5" over on, 327lbs.,,, from memory your bike has solid rear suspenshion, so i wouldn`t be concerned where the swingarm pivot is (low center of gravity can only help high speed stability), however where you are sitting will infulance your rear wheel weight bias,,, remember your bikes body is for dragracing, that is to hold your body weight in one position, and as far forward as praticle, i would suggest that you move ya bum back ,,,, get yourself some good scales and experiment, you`ll be surprised,,, whatever you do always work to 50,50 wheel bias

ben james · Post by **ben james** » Sat Jul 22, 2006 10:00 am

thanks ronnie, yeah that bodywork does hold your bum in one position and also the back of the tank shape stops you getting your guts down and arches your back. took some photos in crouched position and i can't get my back flat. makes sense it being for drag racing as it does hold you in a nice forward position for keeping weight over the front. i imagine when doing a drag start with the front coming up a couple of inches it transfers weight onto the back wheel helping with traction. the easiest solution for me would be to put a zir tank[little 15 litre tank] and ducktail like black betty. have got z1000j bodywork but tank is to big at 21 litres. could then put old style road race full fairing on it. if i used z1000j full length seat and rearset the pegs would be able to position myself quite nicely. might start chasing up a zir tank. might not be able to get this done by next march but as it is a long term project it doesn't matter if i don't get it done straightaway. what do you think ronnie.
ben

ben james · Post by **ben james** » Sat Jul 22, 2006 10:02 am

oh yeah i forgot what type of scales could you use for weiging each end of the bike.
ben

Greg Watters · Post by **Greg Watters** » Sun Jul 23, 2006 12:49 am

I brought a pair of electronic bathroom scales, good to 200kg each, only problem is these need the bike to be positioned within 6 secs of turning on and zeroing :roll:

Stayt`ie · Post by **Stayt`ie** » Sun Jul 23, 2006 9:07 am

greg, fast bike fast scales :lol:

, ben most blokes i know use good bathroom ones (ya need two), i`m luckie as the palmyra dragstrip is only a couple of k`s away, so i just slip over and use there ubueat digital ones

,,,,, mate, i recon ya gunna hava a hard time getting one of them little coffin tanks, also those earlie frames are different to the gpz ones, a lot of panel beating was required to fit the tank to black betty, what model frame is yours :?:

you maybe better off making a new seat/rear section :wink:

ben james · Post by **ben james** » Sun Jul 23, 2006 10:09 am

you're up early ronnie, the frame is a 77 z1000 frame but it has 1.5 litre fuel tank welded where top frame rail would be about 3" diameter. should still be able to get fuel tank over it. should be able to get a tank of a guy called steve hari, he has kawasaki everything. out at the salt i had a cb250rs over the top of the frame and it fitted fairly easy with just a little bit of panel beating. i tried z1000j tank on the frame and it fitted fairly well. just another question , some one told me to be carefull when i take my bike out to dragstrip that with a 8.5" car tyre and dumping the clutch i could twist that non welded crank in the motor thats in it. what do you think. calder park is only 20 mins down the road from my place so i could use their scales. do you weigh one end of the bike at a time or both at once. also i took the bike up the street yesterday and with the camber on the road it made steering the bike with that big back tyre pretty hairy. gotta learn how to ride this bike.
ben

ben james · Post by **ben james** » Sun Jul 23, 2006 3:57 pm

sorry ronnie another question, in that box of stuff there were 2 arias 70mm pistons, underneath they had arias 70k cast into them. i've got a set of 4 with block that are in perfect nick. what i wanted to know if those pistons were z1 or j pistons. the difference is that j piston have the gudgeon pin hole 1.2mm lower as they have shorter conrods. just wondering if you remember those pistons.
ben

hawkwind racing · Post by **hawkwind racing** » Sun Jul 23, 2006 4:28 pm

Ben ,traction or lack of is a fairly involved subject and how we deal with it will always be a compromise ,as it competes with other factors in us going 'fast''there are two forms that effect us primarily.
1.power limited ,when the power we put to the salt (thrust) is greater than the grip afforded by our tyre contact patch and the coefficient of friction of the surface ,I have no idea what that coefficient # is ,I have ben quoted somewhere between 0.4-0.7
2.aerodynamic limited ,when the drag force becomes greater than the grip of the trye contact patch.
The most used method to improve grip is to add weight ,usually as close to the rear axel as possible , this certinatly increases grip ,but it comprises our aerodynamic stability and alters our certer of gravity ,another method that can be used is to use aerodynamic forces themselves, to add extra weight over the back wheel ,with an inverted wing ,again a compramise as it adds considerably to our drag penalty ,which ever method we use ,we must not exceed the load rating of the tyre we use ,or be prepaired to suffer the consequences .
so me must play the compramise game and come up with a design that maximises our ability to go fast within the constrains of the rules ,and people say its a peice of piss to go fast in a straight line .
All I can offer Ben is to look at the design of your bike and decide where you think you will gain the most benifit and play that off against the negatives of that decision , with the power you are making a shorter wheek base would add traction ,look care3fully at Gazza's bike for some clues :wink:

and look carefully at decreasing the frontal area and streamlining look at John Pudneys bike , IMHO thats why I believe no pure drag bike has ever done any fast speeds at the lake
BIG HINT think outside the square :wink:

Gary